FINE-STRUCTURE OF ENERGY-TRANSFER IN TURBULENCE

The energy transfer process in wave-number space is investigated numerically in a forced developed turbulence of Taylor microscale Reynolds number 186 with high symmetry. The energy flow to/from Fourier modes in each wave-number band changes direction repeatedly in time. The inflow and outflow phases align along curves with positive slopes in the (k,t) plane, k being the wave number and t the time. This suggests that the energy is carried step-by-step to larger wave numbers. A blob of modal energy is transferred to larger wave numbers in a way consistent with k is-proportional-to (t* - t)-3/2 as predicted by Kolmogorov's dimensional arguments, where t* is a constant.